#include "cache.h"
#include "pack.h"

static int verify_packfile(struct packed_git *p)
{
        unsigned long index_size = p->index_size;
        void *index_base = p->index_base;
        SHA_CTX ctx;
        unsigned char sha1[20];
        unsigned long pack_size = p->pack_size;
        void *pack_base;
        struct pack_header *hdr;
        int nr_objects, err, i;

        /* Header consistency check */
        hdr = p->pack_base;
        if (hdr->hdr_signature != htonl(PACK_SIGNATURE))
                return error("Packfile %s signature mismatch", p->pack_name);
        if (!pack_version_ok(hdr->hdr_version))
                return error("Packfile version %d unsupported",
                             ntohl(hdr->hdr_version));
        nr_objects = ntohl(hdr->hdr_entries);
        if (num_packed_objects(p) != nr_objects)
                return error("Packfile claims to have %d objects, "
                             "while idx size expects %d", nr_objects,
                             num_packed_objects(p));

        SHA1_Init(&ctx);
        pack_base = p->pack_base;
        SHA1_Update(&ctx, pack_base, pack_size - 20);
        SHA1_Final(sha1, &ctx);
        if (memcmp(sha1, pack_base + pack_size - 20, 20))
                return error("Packfile %s SHA1 mismatch with itself",
                             p->pack_name);
        if (memcmp(sha1, index_base + index_size - 40, 20))
                return error("Packfile %s SHA1 mismatch with idx",
                             p->pack_name);

        /* Make sure everything reachable from idx is valid.  Since we
         * have verified that nr_objects matches between idx and pack,
         * we do not do scan-streaming check on the pack file.
         */
        for (i = err = 0; i < nr_objects; i++) {
                unsigned char sha1[20];
                struct pack_entry e;
                void *data;
                char type[20];
                unsigned long size;

                if (nth_packed_object_sha1(p, i, sha1))
                        die("internal error pack-check nth-packed-object");
                if (!find_pack_entry_one(sha1, &e, p))
                        die("internal error pack-check find-pack-entry-one");
                data = unpack_entry_gently(&e, type, &size);
                if (!data) {
                        err = error("cannot unpack %s from %s",
                                    sha1_to_hex(sha1), p->pack_name);
                        continue;
                }
                if (check_sha1_signature(sha1, data, size, type)) {
                        err = error("packed %s from %s is corrupt",
                                    sha1_to_hex(sha1), p->pack_name);
                        free(data);
                        continue;
                }
                free(data);
        }

        return err;
}


#define MAX_CHAIN 40

static void show_pack_info(struct packed_git *p)
{
        struct pack_header *hdr;
        int nr_objects, i;
        unsigned int chain_histogram[MAX_CHAIN];

        hdr = p->pack_base;
        nr_objects = ntohl(hdr->hdr_entries);
        memset(chain_histogram, 0, sizeof(chain_histogram));

        for (i = 0; i < nr_objects; i++) {
                unsigned char sha1[20], base_sha1[20];
                struct pack_entry e;
                char type[20];
                unsigned long size;
                unsigned long store_size;
                unsigned int delta_chain_length;

                if (nth_packed_object_sha1(p, i, sha1))
                        die("internal error pack-check nth-packed-object");
                if (!find_pack_entry_one(sha1, &e, p))
                        die("internal error pack-check find-pack-entry-one");

                packed_object_info_detail(&e, type, &size, &store_size,
                                          &delta_chain_length,
                                          base_sha1);
                printf("%s ", sha1_to_hex(sha1));
                if (!delta_chain_length)
                        printf("%-6s %lu %u\n", type, size, e.offset);
                else {
                        printf("%-6s %lu %u %u %s\n", type, size, e.offset,
                               delta_chain_length, sha1_to_hex(base_sha1));
                        if (delta_chain_length < MAX_CHAIN)
                                chain_histogram[delta_chain_length]++;
                        else
                                chain_histogram[0]++;
                }
        }

        for (i = 0; i < MAX_CHAIN; i++) {
                if (!chain_histogram[i])
                        continue;
                printf("chain length %s %d: %d object%s\n",
                       i ? "=" : ">=",
                       i ? i : MAX_CHAIN,
                       chain_histogram[i],
                       1 < chain_histogram[i] ? "s" : "");
        }
}

int verify_pack(struct packed_git *p, int verbose)
{
        unsigned long index_size = p->index_size;
        void *index_base = p->index_base;
        SHA_CTX ctx;
        unsigned char sha1[20];
        int ret;

        ret = 0;
        /* Verify SHA1 sum of the index file */
        SHA1_Init(&ctx);
        SHA1_Update(&ctx, index_base, index_size - 20);
        SHA1_Final(sha1, &ctx);
        if (memcmp(sha1, index_base + index_size - 20, 20))
                ret = error("Packfile index for %s SHA1 mismatch",
                            p->pack_name);

        if (!ret) {
                /* Verify pack file */
                use_packed_git(p);
                ret = verify_packfile(p);
                unuse_packed_git(p);
        }

        if (verbose) {
                if (ret)
                        printf("%s: bad\n", p->pack_name);
                else {
                        use_packed_git(p);
                        show_pack_info(p);
                        unuse_packed_git(p);
                        printf("%s: ok\n", p->pack_name);
                }
        }

        return ret;
}